1. Field of the Invention
The present relates generally to devices that utilize a cryogenic aerosol spray to remove particulates from substrates and the like, and more particularly to devices and methods for reducing the effect of tribocharges that may occur during such a spray cleaning operation.
2. Description of the Prior Art
The removal of micron-sized contaminating particulates from the surfaces of substrates is a significant problem encountered in the semiconductor fabrication industry, as well as other industries where micron-sized particulates are of concern. One system for the removal of such particulates utilizes a cryogenic aerosol spray, typically carbon dioxide, that is sprayed onto the substrate surface. The cryogenic aerosol is sprayed from a nozzle in a high speed liquid stream and forms solid particulates, termed a snow, following emission from the nozzle. The snow and perhaps some liquid impact the contaminating particulates to mechanically remove them from the substrate surface to clean the surface.
A significant problem of electrostatic charge build-up has been encountered utilizing the cryogenic aerosol cleaning methods. Particularly, because the material that comprises the cryogenic aerosol, typically carbon dioxide, and the material of the substrate surface, such as a metal, or an insulator, differ with regard to their position on the triboelectric scale (also known as the "work function"), a significant triboelectric charge or tribocharge can be created during the cleaning process. The tribocharge can result in significant electric fields and electrostatic discharge which can damage sensitive components of the substrate.
One solution to this problem has been to ground the metal chuck which supports the substrate within a cleaning system. However, the inventors have discovered that the grounded chuck does not adequately resolve the tribocharge build-up. A need therefore exists or an improved device and system for reducing the effects of tribocharges during a cryogenic aerosol, spray cleaning operation.